1. Field of the Invention
The invention concerns a component of low overall height for circuit boards having a magnetic region formed by at least one layer made of a soft-magnetic material.
2. Description of the Related Art
A component of this type is known from U.S. Pat. No. 5,529,831. The known component is produced by applying insulator films, conductor films, and a magnetic film onto the substrate. A typical sputtering process is used to apply these films.
A disadvantage of this type of component is that it can only be produced with the aid of a costly thin-film process. In addition, depending on the process, only low film thicknesses in the range of a few xcexcm can be produced. The cross-sections of the magnetic regions produced with the aid of this process are correspondingly small. A further disadvantage is that with this type of component, the windings must also be produced with the aid of a costly thin-film process.
Proceeding from this prior art, the object of the invention is to create an easily producible component of high inductivity for use on circuit boards.
This subject is achieved according to the invention in that the magnetic region is formed by at least one soft-magnetic sheet. The surface roughness of each sheet is at least equal to the skin penetration depth at the usage frequency.
Magnetic sheets can typically be produced with thicknesses in the range from 10 to 25 xcexcm. If they are stacked on top of one another, significantly larger cross-sections of the magnetic region than those of magnetic regions produced in thin-film processes thus result. As a consequence, the inductivity of a component equipped with this type of magnetic region is relatively high. Nonetheless, the component according to the invention has a low overall height and is therefore also suitable for SMD technology in this regard. It is particularly favorable for high frequency applications that the surface roughness of each sheet is at least equal to the skin penetration depth at the usage frequency.
Further embodiments and developments are the object of the dependent claims.